Yeah and often when they are chasing them they circle the sky like you described. I witnessed a group of crows chase a hawk off once and they had that poor hawk doing laps all around the sky until ot finally turned tail and ran (well, flew
). I've also heard them freak out without ever seeing the hawk. I know it's hard to believe if you saw the crows hanging around but I highly doubt a crow or group of them took your bird. Even a bantam. They're pretty big for crows. HOWEVER. If a hawk or other predator already killed your bird then yes, they could have been circling to eat it. They're not going to discriminate or be picky about a food source (to them that's what it is, however sad). But I highly doubt they actually killed your bird
